1. Field of the Invention
The present invention relates to an air drill, and more particularly to a portable air drill capable of changing its rotational direction.
2. Description of the Related Art
A body of a conventional portable air drill capable of changing its rotational direction comprises a grip portion which has an air supply passage and an air exhaust passage formed therein; a trigger portion which is formed above the grip portion and supports a trigger; and a cylinder portion which is formed above the trigger portion and accommodates an air motor therein.
A lock ring is threadingly engaged with an open end of the cylinder portion. A spindle is disposed inside the lock ring via bearings. A reverse valve is disposed within a closed end portion of the cylinder portion, opposite the open end thereof.
The reverse valve has a single reverse lever. Rotational direction of the air motor can be reversed through switching the reverse lever. The reverse lever is slidably attached to a slit-shaped opening formed at the closed end portion of the cylinder portion.
However, in the case where the conventional air drill is placed on a table or the like, if for some reason an air hose connected to the grip portion is pulled, the air drill may fall on the floor, and the body may be broken.
The above-described breakage occurs for the following reason. Since the air drill assumes a pistol-like shape, when the air house is pulled and the air drill falls on the floor, the air drill falls on the floor in such a posture that a crack is generated in a portion adjacent to the opening, where impact stresses concentrates, and the crack leads to breakage.